1. Field of the Invention
This invention relates generally to an automatic transmission for motor vehicles having a hydraulic torque converter, an auxiliary transmission mechanism forming an overdrive or underdrive (reducing) mechanism and a main transmission mechanism with a plural number of forward ranges and a reverse range, and more particularly to an automatic transmission for front engine-front drive type motor vehicles (hereinafter referred to as "F.F. vehicles" for brevity) which have axle shafts of front wheels driven from a transversely mounted internal combustion engine having its rotational axis disposed transversely to the body length of the vehicle.
2. Description of the Prior Art
In an automatic transmission for motor vehicles, a hydraulic torque converter and a transmission gear mechanism with a number of forward ranges and a reverse range are generally coaxially coupled with the crankshaft of an internal combustion engine.
In F.F. vehicles having the crankshaft of an internal combustion engine disposed transversely of the vehicle body, it is the usual practice to mount also in a transversely oriented position a block which assembles together an internal combustion engine, a torque converter and a transmission gear mechanism. However, in a case where an automatic transmission of this sort is mounted on a small motor vehicle which has a limited engine room space, a difficulty is often encountered in finding a space for an auxiliary transmission mechanism such as an overdrive or underdrive (reducing) mechanism which serves to improve the operational efficiency or to increase the speed ranges of the transmission, or a space for mounting a direct-coupling clutch to the hydraulic torque converter for improving the fuel consumption.
What is needed is an automatic transmission for a front engine-front drive type motor vehicle which includes an auxiliary transmission mechanism such as an overdrive or underdrive mechanism and a direct coupling clutch for the hydraulic torque converter for improving fuel consumption.
SUMMARY OF THE INVENTION
It is a primary object of the present invention to provide a compact automatic transmission for motor vehicles having, along with a hydraulic torque converter and a main transmission gear mechanism with a plural number of forward ranges and a reverse range, an auxiliary transmission gear mechanism constituting an overdrive mechanism of a speed reduction ratio smaller than 1 or an underdrive mechanism having a speed reduction ratio greater than 1.
It is another object of the present invention to provide a compact automatic transmission for motor vehicles of the type mentioned above, in which the auxiliary transmission mechanism is provided coaxially with the hydraulic torque converter and in parallel relation with the main transmission mechanism, transmitting power from the torque converter to the main transmission mechanism through the auxiliary transmission mechanism.
A further object of the present invention is to provide an automatic transmission for F.F. vehicles, in which the output shaft of the main transmission mechanism, positioned in parallel with the auxiliary transmission mechanism, is coupled with axle shafts of front wheels through a differential gear device.
According to the present invention, there is provided an automatic transmission for motor vehicles having a hydraulic torque converter, an auxiliary transmission mechanism mounted coaxially with the torque converter, means for transmitting power from the torque converter to the auxiliary transmission mechanism, a main transmission mechanism having a rotational axis in parallel relation with the rotational axis of the auxiliary transmission mechanism and having a plural number of forward ranges and a reverse range, means for connecting the output shaft of the auxiliary transmission mechanism with an input shaft of the main transmission mechanism, and means for connecting the output shaft of the main transmission gear mechanism with axle shafts of front wheels through a differential gear device, whereby the auxiliary transmission mechanism constituting an overdrive or an underdrive (reducing) mechanism is mounted additionally to a conventional automatic transmission having a hydraulic torque converter and a transmission mechanism with a plural number of forward speed ranges and a reverse range, without increasing longitudinal dimensions of the transmission. Mounting on a small-size motor vehicle is practicable while augmenting the speed ranges of the transmission. Moreover, the transmission construction still has room for providing a direct-coupling clutch for the hydraulic torque converter, so that the fuel consumption of the motor vehicle is improved by providing the direct-coupling clutch together with the auxiliary transmission mechanism in the automatic transmission.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
The invention according comprises the features of construction, combination of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.